Electrical protective device



Se t. 24, 1929. H. ROVERE ET AL 1,729,053

ELECTRICAL PROTECTIVE DEVICE Filed May 19, 1925 2 Sheets-Sheet 1 mum- In ngwucnl om [ewis ff zPovez-e Everett VT Mott Baewt C, Aya

Sept. 24, 1929. 4 L. H. ROVERE ET AL 1,729,053

' ELECTRICAL PROTECTIVE DEVICE Filed May 19, 1925 2 Sheets-Sheet 2 [e wzls E ZPovare Everett V Mote may: 6. Aye/us Patented Sept. 24, 1929 LEWIS H. ROVERE, F RICHM NDrINEW Y EVERETT mom, OF .METUC-HEN,

' unvtrannsnxnnnnonnnr o. AYERS, or- BROOKLYN, nnwycmz, Ass-IsNoRs'ro 'This invention relates to devices -'foi 'pro-, tecting electricalcircuits, such as telegraph andtelephonelines, from the destructive actionjof heavy/potentials or charges due'to electrical disturbances of any kinds The type'ci arresters commonly employed breakdowns which'might'result from ex- "cesjsive voltages arising from lightning 'or vertical sectional views of permanently assembled arrester's corresponding to the 4 constructions shown in'Fgures 2 and 9, respectively;Figures.15 and 16 are, respectively,

:side and end elevations of the line/block elec-- to protect cables and "apparatus against static charges and from accidental contacts' between the telegraph or telephone-line wires "and "high tension conductors usually con- I 4 electrode 21 molded therein. Thennolded sist of two electrodes of metal or carbon separated by avery narrow air -ga.p, the thickness of which is'accu'ratly arator of insulating material. I Our object of the present invention is to provide a protector oftheopen space type in maintained by a sep which the air-gap is accurately determinedby the construction of the electrodes without the use of separators'or other spacing devices. a A further object is toprovide an arrester or protective device in which the time required for the grounding of the arrester as a result of arring between the two electrodes maybe closely predetermined and controlled by varying the shape or arcing contour of one of the T I shoulders22 and with a'hole 23 into which the scription, Figures 1, 2 and 3 area top plan, a longitudinal section and an end elevation,

respectively, of one form of our inventiony p I tpcrrng sides 21. The lateral edges may also be' chamfered as ndicated at 21*. We

Figures 4; and 5 are atop plan and a side elevation, respect1vely,.of the ground block or electrode shown in the previous figures; Fig

top plan and and 8; Figure 9 is a longitudinal vertical sectrodes to come into contact to'form a complete tional view of a. further n'iodification: Figure 10 is a top plan view of the ground electrodeor plate shown in Figure 9; Figures 11 and 12' ture; Figures 13 and 14 are longitudinal- -trode insert; and Figures :17, 18, and 19 are respectively a top plan, a side elevation, and an end elevation of the ground block fastening plate.

v A protector or arrester embodying the tea-' tures of our invention comprises a line block composed. of insulator-:member; 20 with an insulator member maybe composed of a material which softens between 150 andinsulating material may flow torigidly keep the electrodein position. The block is proi vided as usual with end flanges 20 and outwardly extending side flanges 20 The electrode "is preferably 'jmade with have discovered that by varying the shape of the-electrode 21, as by modifying the taper of the sides and also by changing the diameter of the central hole, we can vary the time required for the grounding of the arrester as a result of arcing between thetwo electroces. This period of time required for the elecconduct ing path and ground the arrester after'the arc has been established between the electrodes may be varied-over quite a wide range. This time interval can be varied by the tapering of the sides because as the line electrode moves toward the other electrode, an'increasing amountof the insulating body holding the electrode must be moved or expanded. Likwise the time interval can be altered by varying the size of the hole in the body of the electrode, since this varies the 5 amount of materialwhich must be softened or grounding and we are-thereby enabled to desi n and construct arresters which are re- 0 b 0 e a quired to operate under d fferent conditions.

After the line block has been molded the' inner surfaces of the insulator endsand the electrode are accurately ground flush to the --same plane. In the forms shown in Figures 1,

2and'12, the cooperating electrode or ground block 25 consists of a plate or block of carbon or other suitable refractory conducting material. The opposite faces are hollowed or a ground to form a depressed area 26, accurately of uniform depth to provide exactly the desired air-gap betweenthe two electrodes when the parts are assembled.

In the form shown in Figure 6, the ground block or base block 28, which constitutes the cooperating electrode, consists of a metal plate of suitable material which is stamped into the shape indicated in Figures 7 and 8 with side and end flanges to snugly fit about the edges of the line block, the central portion being depressed, preferably with a marginal groove. 29, the middle part 30 being accurately gauged to leave the proper air-gap with the electrode 21 when the parts are assembled.

The form shown in Figure 9 differs from Figure 6 in having the entire body of the 7 sheet metal electrode 28, forming the ground block, within the flanges in the same plane,

4o. the airj-gapbeing formed by small projections 32 stamped .up at opposite ends. Theseprojections may be made very accurately so that I i the electrodes will be exactly correct when the parts are assembled.

The forms shown on sheet 2 of the draw-. L ings differ from those shown on sheet 1 in having the assembled parts of the arrester {permanently fastened together. In the forms shown in Figures 11 and 14, the sheet metal fio-ground electrode or block is provided with a- I tongue 34 at each end, which is bent over the. end flanges of the insulating member of the 1 ,line block. I In the form shown'in Figure 13, an additional sheet metal member 36 is provided having side and end flanges to encase the sides and ends of theground block or electrode 25,. the end flanges having tongues 34 which are bent over the ends or into notches in the ends of the insulator part of the line block to securely fasten the parts of the protector t0- gether. V

\Ve claim becoming plastic when heated above a predetermined temperature, said body having a recessed inner face with end bearing surfaces, an electrode molded in said body and having its inner portion wedge shaped and protruding within said recess, said: protruding portion having an extended plane surface between the inclined end surfaces, and an opposing electrode. comprisinga i'conducting block or plate having bearing portionsito engage said bearing surfaces :and a Jcentral plane surface spaced :frorn-said firstenamed plane surface a distance equal to the desired arcing air-gap.

2. A protector for electric circuits, comprising a molded body of insulatingw material becoming plastic when heated above a predetermined temperature, said body-having a recessed-inne'r'face with end bearing surfaces, an electrode molded in said body and having .an inner wedge-shaped. portion, the innermostpart of said wedge-shaped portion protruding into said recess, and an opposing electrode comprising 9. conducting block or plate engaging said bearing surfaces and spaced fromthe inner surface of said electrode a distance equal-to the desired arcing air-gap. 1

3. A protector. for electric circuits, comprising a molded body of insulatingmaterial becoming plastic whenheated above a predetermined temperature, said body having a recessed inner face with end bearing surfaces, an electrode moldedin said body and having an inner wedge-shaped portion, the innermost part of said wedge-shaped portion p'rotruding into said recess,-the opposite edges of said wedge-shaped portion being inclined at an angel to provide a predetermined interval between the softening of the insulating anolded body and :movement .of g the elec- 

